This disclosure relates generally to proximity detection systems at work sites, and in particular to proximity detection systems that allow system response to be altered depending on the particular operational situation.
In industrial settings, personnel are often required to work near moving machines and vehicles. Much too often, workers are injured while doing their jobs. As more equipment is used and as that equipment has become larger and more powerful, and as the operations have become more complex, many of the injuries and fatalities result from workers being struck or crushed by the moving machines/vehicles or by collisions between vehicles.
Many methods have been devised to warn people against being struck, pinched, crushed or otherwise harmed by vehicles and mobile equipment. Unfortunately, the systems that have been devised to help protect people and property in these industrial operations, such as proximity detection and collision avoidance systems, have usually not been very effective. A new proximity detection system was developed and successfully demonstrated for use on continuous miners, as disclosed in U.S. Pat. No. 7,420,471 (the '471 patent), U.S. Pat. No. 8,169,335 (the '335 patent) and U.S. Pat. No. 8,232,888 (the '888 patent), and U.S. patent publications 2009/0322512 (the '512 publication) and 2010/0271214 (the '214 publication), which patents and publications are herein referred to collectively as the “Frederick patents,” the disclosures of which are incorporated herein by reference in their entireties. An objective of the '471 patent is to help prevent the crushing or pinning of personnel who are remotely controlling a continuous miner, and to help protect other personnel assisting in use of the continuous miners. The '471 patent also envisions to provide protection to personnel from other types of mobile equipment and machines. The system of the '471 patent employs a magnetic marker field and an active architecture that incorporates two-way communication between the worker and the machine the worker is near. Warnings are given to workers that are too close to the miner. Warnings are also provided to the operator of the machine. Provisions are made to immobilize the equipment until personnel were able to reach a safer position.
The magnetic fields used in the '471 patent system oscillate at low frequencies and can be effectively used to mark off warning zones, danger zones and silent zones. Although the maximum practical range of such low frequency magnetic fields may be as much as one hundred feet, in most applications that is more than is needed or desirable for most equipment. Typical very large off-highway haul trucks would probably be best served with a warning zone in the range of eighty feet and a danger zone in the range of thirty to forty feet. In some applications, such as remotely controlled continuous miners, it is necessary for the operator to remain within a range of five to ten feet much of the time in order to maintain good visual contact with the machine and the immediate surroundings. The zones are shaped to be longer in the direction of travel or movement but less in directions perpendicular to the direction of travel. In underground mines, the low frequency magnetic fields pass through earth formations unimpeded so that a worker that is around a corner, not in line of sight, or otherwise obstructed, will still be visible to the marker field. These magnetic fields do not radiate from antennas but simply expand and contract around the element that produces them, and are well suited for marking boundaries between silent zones and warning zones.
The invention is particularly applicable to work sites that require personnel to be in close proximity to various hazardous elements, such as machines, mobile equipment, remotely controlled machines, and operated vehicles. Such work environments may include locations that are inherently dangerous and should be avoided or entered only with great caution. Examples of such work environments are surface mining, underground mining, sand and gravel operations, road construction, warehouses, shipping docks, coke plants, factories, industrial sites and other environments. Hundreds of people are killed each year in the U.S. in such work environments. Workers are sometimes struck, pinched, crushed or otherwise harmed while performing their jobs in such environments. Collisions between the various elements at the work sites need to be avoided also to avert property damage.
Referring now to FIG. 1, there is illustrated a simplified example of a work site in which a proximity detection system is implemented. FIG. 1 shows a truck 304 on which a magnetic field generator (MFG) 81 is mounted. The magnetic field generator 81 generates a magnetic field 92 that surrounds the truck 304. The edge of the magnetic field 92 generated by the magnetic field generator 81 corresponds to a magnetic field strength defining the border of a Warning or Danger Zone (safety zone) surrounding the truck 304. A worker 301 within the boundary of the Warning or Danger Zone 92 is in potential danger from being struck or otherwise injured by the truck 304. The worker 301 carries a personal alarm device (PAD) 60. If the worker 301 and, correspondingly, the personal alarm device 60 are within the magnetic field 92 created by the magnetic field generator 81, the personal alarm device 60 detects the presence of the magnetic field 92 and issues a visual or audio warning. In embodiments of the magnetic field warning system, as detailed in the '888 patent, multiple magnetic field generators 81 may be used to generate Warning and Danger Zones having a complex shape around the truck 304 or other equipment or areas. These zones may be adjusted in both size and shape. In addition, safe zones may be designated near the truck 304 in which a personal alarm device 60, while within the magnetic field 92, does not generate a warning signal to the worker 301.
FIG. 2 is a diagram of the personal alarm device 60 and the magnetic field generator 81 of the proximity detection system of FIG. 1. A magnetic field generator 80 is contained within a housing 81 and includes an amplifier 84 connected to a ferrite core 90, inductor 86 and capacitor 88. In addition, the magnetic field generator 80 is connected to a power source 83 that provides the power to operate the magnetic field generator 80. The amplifier 84 is connected to and controlled by a controller 82. The ferrite core 90, inductor 86 and capacitor 88 generate a magnetic field 92 in response to an input voltage from the amplifier 84. The amplifier 84 is controlled by the controller 82 which controls the voltage and current outputs of the amplifier 84. The controller 82 is also connected to a receiver 96 and warning system 98. The receiver 96 is connected to an antenna 94 which receives an input signal 76 from a personal alarm device 60. The antenna 94 conveys the signal 76 to the receiver 96 which passes the signal 76 to the controller 82. Upon receiving the signal 76 from the personal alarm device 60, the controller 82 directs the warning system 98 to issue a warning. In one embodiment, the warning system 98 may issue an audio and/or visual warning. In another embodiment, the warning system 98 may be capable of terminating the operation of a vehicle to which the warning system 98 is mounted, for example, the truck 304 of FIG. 1. The magnetic field generator 80 may also be mounted in a location in which it is desirable to warn a worker carrying a personal alarm device 60 of their proximity to the location.
The personal alarm device 60 has x, y, and z axis magnetic field antennas 62 that sense the magnetic field 92 produced by the magnetic field generator 80. The sensed magnetic field signal 80 is passed through filters 66 and an amplifier 68 to a signal detector 64. The signal detector 64 then passes information about the detected signal to a controller 70. The controller 70 activates a transmitter 72 which transmits a corresponding response signal 76 to the magnetic field 92 through an RF (radio frequency) antenna 74. In one embodiment, the response signal 76 is an RF signal. The personal alarm device 60 is powered by power source 71. The personal alarm device 60 is carried by the worker 301 (FIG. 1) in order to provide the worker with a warning of their proximity to a magnetic field generator 80.
In such work sites, it is often necessary for workers and vehicles, such as fork lifts and lift trucks, to share the same work space. For example, workers may need to work near machines that must be serviced with supplies, materials must be delivered to worker's areas by fork trucks, etc., or vehicles may need to retrieve materials, finished products, or waste products from machines where workers are employed. However, it is also often the case that workers and vehicles must share a space, but should not concurrently be in this space. Thus, there is a need for new capabilities that will retain the safety benefits of the known proximity detection devices while allowing how MFGs and PADs respond to the operational situation to be altered, e.g., in order to ensure that workers and vehicles are not concurrently in the same area or in order to avoid false alarms in a situation where it is desired that the worker be near the vehicle/equipment.
Proximity Detection Systems and Collision Avoidance (PDS/CA) systems are being implemented on Powered Industrial Trucks such as Fork Trucks and Clamp Trucks, conveyors, haulers, personnel carriers, a wide variety of mining equipment, and other equipment. These safety systems typically give warnings to operators that the machine or vehicle is a threat to the safety of someone and gives warnings to those being threatened. They also help avoid collisions between vehicles, between vehicles and objects, or to keep the vehicles out of certain areas. They may also record information related to accidents or accident-prone conditions, or may even transmit information real-time for monitoring and tracking. The current disclosure is related to providing safety protection in highly mechanized areas and will normally be used in support of or in combination with PDS/CA systems.
Although some currently available PDS/CA systems are a very effective and practical means for reducing “hit-by” accidents in most parts of a facility, there may be highly mechanized areas where special circumstances may cause PDS/CA systems to be ineffective or to not be usable. An example would be where there are large fixed-place machines being operated by workers, mobile machines working around the fixed machines, pedestrians working in the area, and other personnel having to pass through the area for other reasons. Loading docks where pedestrians and fork trucks must work closely together can also create complex operational scenarios. Another example would be intersections where both machines and pedestrians must frequently cross paths. Another case is when fork lifts go between storage racks to store or retrieve pallets of items from the racks and workers are in the same area, even on the opposite side of the racks. Magnetic fields produced by a PDS/CA system may extend through the racks and warn a pedestrian or other mobile machine when they are perfectly safe, separated from the fork truck by the racks. The use of PDS/CA systems in these areas, and many other situations that could be listed, may be confusing, may even be disruptive to normal work and can seriously impact production. The central problem is that many alarms are given and safety is not significantly improved.
Although these mechanized locations usually involve only a very small part of a facility or industrial operation, sometimes they are the highest “hit-by” risk areas so that protection is greatly needed there. The current disclosure provides a mechanized area controller (MAC) for pedestrians and mobile machines in mechanized areas to be better protected while to a lesser degree or not at all impacting productivity or causing confusion.
There is a related reason that the present disclosure may be very important for some industrial settings. Even though PDS/CA systems can be successfully deployed throughout the majority of a facility, pedestrians and mobile machines that are effectively using those systems must from time to time, if not frequently, enter those relatively small areas where these systems would either be ineffective or disruptive to production and confusing. Therefore, facility managers can be discouraged from using PDS/CA systems to provide added safety for their workers and equipment in the large majority of their facility because of the complications in one or a few small areas. Yet, after extensive steps have been taken to try to eliminate “hit-by” accidents by more conventional means, employing training, procedures, signs, markers, and lights, accidents still occur and the managers seek a solution. A manager may consider taking drastic actions such as installing governors to slow down all mobile machines at all times. Slower speeds may reduce the frequency of some types of accidents but slower speeds may have a severe impact on production. Faster machines do more work. The present disclosure makes it more practical to deploy PDS/CA systems throughout a facility by making the PDS/CA system more useful and usable in even the more complex situations. The present disclosure utilizes system elements that cooperate with each other, and provide or interact with safety devices on mobile machines and safety devices being carried by pedestrians. These devices also provide signals to activate facility-provided warning systems. Although PDS/CA systems currently in use in mining and other industrial operations are described in detail in the Frederick patents, as well as in commercial literature, a brief review of key functional features of a PDS/CA system should be helpful to understanding this invention.
An example of a situation where PDS/CA systems are known to be effective would be a person walking behind a fork lift, not being noticed by the operator, the person being hit when the fork truck backed up. Or, a pedestrian steps out from behind an object into the path of a fork truck. Although training, procedures, and passive safety measures greatly improve safety, there still are thousands of personnel who are seriously injured by fork trucks in the US each year by simple situations. About 100 personnel are killed each year in the US, by fork truck accidents. Technology, such as PDS/CA is required to make significant reductions of “hit-by” accidents.
FIG. 4 is a diagram of a more complicated work site 100 in a warehouse, showing two fork trucks 101, 103 and a pedestrian/worker 102, where an accident can occur. Although the driver of Fork Truck 101 can easily see the pedestrian 102, and will almost always avoid hitting the pedestrian 102, sometimes the pedestrian may make an unexpected change in direction and be hit. The operator of truck 103 however cannot see the pedestrian 102 because his view is blocked by tall storage racks 104. If the pedestrian 102 were to step out in front of the truck 103 and the operator of truck 103 were to be distracted by other tasks or other events, then the pedestrian 102 might be hit. If both trucks 101, 103 are moving toward the junction where they will cross paths, they could collide. The operator of truck 101 might be distracted in passing the pedestrian 102 and drive his/her truck into the path of truck 101. Many other scenarios could occur with this kind of situation that could result in a pedestrian being hit or of trucks colliding.
Note the elliptical dashed line 107 around Fork Truck 101 and the similar line 108 around Fork Truck 103. These lines represent the magnetic field strength defining Warning level safety zones that are produced around these vehicles by the PDS/CAs on each truck. Commercial literature shows that a typical size of these elliptical fields at the warning level may have a major radius of about 44 feet. The settings in Personal Alarm Devices for the Danger level would normally be set to correspond to a major radius 60%-70% of the major radius for the warning level. This range may be adjusted for differing machine sizes and special operational considerations. The minor radius of line 107 will always be about 80% of the major radius, or about 30 feet in this case. The parameters are similar for line 108. The most effective tool for establishing these zones is using magnetic field generators 109, 110. Other techniques such as Radio Frequency transmissions are sometimes used but are less precise and less reliable. When the magnetic field represented by line 107 reaches sufficient strength at the pedestrian 102, the Personal Alarm Device (PAD) carried by the pedestrian 102 senses the proximity of the truck 101 and produces visible and audible alarms to the pedestrian 102. These alarms can have more than one level and may depend on magnetic field strength, the first being an initial warning and a second being a more intense warning signaling a greater danger. At the time the pedestrian 102 is warned, the operator of truck 101 is also given an alarm. Thus, both the pedestrian and the truck operator have warnings to give them an opportunity to take action to avoid an accident. Similarly, the magnetic field around truck 103 will also warn the pedestrian 102 and result in a warning to the operator of truck 103. Likewise, the operators of the two trucks 101, 103 will each be given a warning that they are approaching each other. The details of how these warnings are provided are included in the Frederick patents and commercial literature. The current invention is a system that manages, coordinates, and controls the movements of personnel and equipment in areas which are mechanized, and incorporates the inherent capabilities of well-designed PDS/CA systems.
It should be noted that the use of low frequency magnetic fields to establish the safety zones has been shown to the most effective available technology and will be assumed as the type of PDS/CA system included in and/or used in cooperation with the current disclosure. This invention could be adapted for use with other types of PDS/CA systems, such as RFID, by making certain changes and additions, if such other system technologies were to be improved to have sufficient precision and reliability.
The MAC could also be used in robotic areas where some or all of the operators are replaced by computers and pedestrian functions are performed by robots. Whether the operator is a person or a computer with appropriate sensors will not have a material effect on the functional value of the MAC system. Higher levels of automation would affect details about how warnings were issued and interpreted.